Recently, a polyurea paint containing polyamine and polyisocyanate has been used widely for fast reactivity, and mechanical property, chemical resistance in a cured product, and the like. Particularly, the polyurea paint using as a polyamine polyaspartic acid ester has attracted a lot of attention in the viewpoint of appropriate curable rate, and the possibility of making the coating more thick (for example, Non Patent Document 1). Therefore, the used amount of the polyurea paint has been increased in a market. In addition, a polyurea resin obtained from a polyaspartic acid ester has attracted a lot of attention in the application other than paint in the viewpoint of good mechanical property. However, a cured product (polyurea resin) obtained from a polyaspartic acid ester has problems such as fragile and easy cracking properties. On the other hand, effective means of lowering fragile property, that is, improving toughness without greatly affecting on other property (for example, appearance) has not been found in the present state.